DE1549759C3 - Circuit arrangement for displaying characters on the screen of a cathode ray tube - Google Patents

Description

The invention relates to a circuit arrangement for the line-by-line display of characters on the Screen of a cathode ray tube in a grid field with several columns of characters for each character and contains at least one spacing column forming the separation distance between two characters, by lightly scanned video signals during the same time sequence that form the columns vertical beam deflections with a simultaneous horizontal beam deflection, consisting of from an A "sawtooth generator that sends the beam in a horizontal direction over the length of the line leading deflection signal generated, a Y-sawtooth generator, which the the beam in the vertical direction Generates signals deflecting over the height of the characters, a character generator that runs at equal time intervals Supplies clock signals to the Y-sawtooth generator and video signals for the picture tube and one Timing circuit for synchronizing the deflection and video signals.

The purpose of this invention is to provide an improved character display system, in which the legibility of the on the screen by characters, for example letters, numbers or symbols, between displayed information by providing wider horizontal separations the adjacent characters is improved without reducing the number of characters on the screen characters to be displayed is restricted or that an increase in the capacity of the Information receiving memory is required or that changes in which the information delivering system are required, which can be, for example, an electronic computer.

With certain data processing systems, where a quick communication between the operator and the computing system and "real-time" access to the data information is required display devices are used to display characters. The ability of the display devices to process data or to provide information from the data processing system earlier than printer devices, makes it possible for these display devices to be used in industry, science and administration and found in other areas. As a peripheral device, several display devices can be connected, which can be controlled by a common control unit are. Such a control unit includes a character generator as a most essential element. This

Character generator has the task of the display devices connected to the control unit To control beam deflection, or it interacts with a memory in which the character generator supplied video signals may be saved for possible subsequent character display will. The present invention will be described in terms of a system which acts as an information store has a runtime memory. Display devices of the type mentioned above use for Character representation a grid which is similar to the grid used in television technology, in which during the electron beam deflection by the video signals in a certain order the electron beam is lighted depending on the character to be displayed. at the display devices used to display information on which the above invention is based, the characters to be displayed are preferably generated line-by-line in a point probe, that in the writing process, while the beam is guided in a horizontal direction across the screen, the beam also at equal time intervals in the vertical direction, at least the height of the characters accordingly, is deflected. These vertical deflections correspond to the symbols and Distance columns in the grid. Each character that can be represented is assigned characteristic video signals, by which the beam is preferred during the vertical excursions corresponding to the character columns is lightly scanned in a punctiform manner. These light-touched points in the character columns of a character grid form the character to be displayed.

In a known display system on which this invention is based, for example, for a character uses a 5 x 7 grid of points, i.e. That is, the character consists of five vertical columns of characters, where each column of characters can contain seven light buttons.

Each character to be displayed is in the character generator or in the runtime memory in a block, the corresponds to a character grid. This block is also divided into several equal fields, which correspond to the character columns and the spacing column. In the field columns of the Blocks, which are assigned to the character columns, are the characteristic video signals for the individual Characters included. The field column that corresponds to the spacing column does not contain any video signals. In the known representation system mentioned above, each character occupies in the character generator or runtime memory a block consisting of six fields, each block seven Can hold video signals in coded form. However, the encoded video signals are only in the first five fields, which correspond to the five character columns, while the sixth Block remains free because it corresponds to the spacing column.

A time control circuit connected to the character generator generates a message with each field or a grid column corresponding control or clock signal generated, which is used to synchronize the horizontal and vertical beam deflection signals and the video signals. This at the same time The clock signals appearing as a result ultimately cause the vertical deflection of the electron beam, at which the light keying takes place through the video signals, whereby the beam is also at the same time in the horizontal Moving direction. The characters thus displayed on the screen in a known manner are not easy to read because the horizontal separation distance between two adjacent characters of the same width only corresponds to a character column. Display devices with a character representation according to the above Explanations are not satisfactory due to the poor legibility of the information displayed: The horizontal spacing between characters is too narrow and the information displayed appears washed out and ambiguous. Some solutions for elimination that are obvious to a person skilled in the art of the jacket and to improve the image quality would be: A reduction in what can be displayed in one line Characters to get larger spacing, which however reduces the display capacity results. Or the field column in the block of the character generator or runtime memory is enlarged, so that the clock signal for the spacing column appears later and an unequal clock sequence for the vertical beam deflection and thus a larger separation distance between the characters results. Even this change results in a reduction in the number of characters that can be displayed on the screen and an increase in size the capacity of the character generator or the runtime memory. Such a measure However, this would also impair the image quality, since the image cycle would also be longer which would cause the display to flicker. Another reason for failing to do this Changes is that the data processing systems, the information sequence in the initially mentioned manner is offered by the character generator and that such changes because of the high expenditure, especially with the data processing systems already on the market are not practically feasible.

A character generator for the raster-shaped representation of Characters on the screen of a cathode ray tube are known for each character as well a grid field is provided which contains several character columns and a spacing column. The character representation also takes place with a uniform horizontal deflection of the electron beam by a sawtooth-shaped deflection signal. Even this known arrangement has the disadvantage of poor legibility of the characters, since the spacing gaps in width is equal to the width of a column of characters. With such an arrangement, the individual characters, as explained above, are difficult to distinguish from one another.

In addition, according to US Pat. No. 3,210,599, there is a “two-speed deflection system for displaying characters on cathode ray tubes «, in which the horizontal deflection of the electron beam takes place by two deflection systems of a special tube. At a first deflection system, which is the usual ^ Deflection system, a sawtooth-shaped deflection is used for the horizontal beam deflection and placed a relatively low frequency deflection signal. At the second deflection system there are two different ones Signals placed, one of which is used for analog writing of the character to be displayed and the other to position the character on the screen. This last-mentioned deflection signal is also sawtooth-shaped and has a relatively higher frequency

5 6

are superimposed on as the Z deflection signal of the first deflection sy- rator and that the amplitudes of the

stems. The higher frequency signals are selected in their superimposed sawtooth pulses so that

number equals the number of in a row or in that after the superposition the resulting horizontal

characters to be displayed in an X deflection cycle. zontal beam deflection speed in the character through the simultaneous action of the X-deflection 5 cleave more slowly and in the spacing gaps

gnals and the relatively higher frequency sawtooth signals is faster, so that compressed distances

there is a resulting horizontal deflection field between the character columns and spread deflection

for the electron beam, which results in a staircase at the gap,

has a moderate course. In the respective planar screen devices improved like this, which with

run of the resulting deflection field, i.e. verse in the case of the circuit arrangement according to the invention

Slope 0, if the contours are to be plotted, they should be used as a reliable, cheap mass pro-

sign. After a mark has been written, it can be produced, for example in schools

chens the electron beam jumps to the next as a teaching aid or in commercial offices as

Writing point that can be used through the staircase-shaped information device,

of the horizontal deflection field is determined. 15 To an economical cheap manufacture of this

To enable this known method for stepwise horizontal display devices, it is expediently zontal Deflection of the electron beam is for borrowed, simple and well-used components analog writing of characters. However, to use circuitry which is also external it is expensive, since two deflection systems are operated half of their linear range, whereby and a special tube is required. This distortion and nonlinearities that occur driving is not applicable to the representation of by means of compensation devices, feedback signs according to the raster method with video signal circuits or others known to the person skilled in the art len (in which, for example, a character to be displayed is eliminated from resources in order to obtain a reliable long five Columns of characters is formed), because with the time function to be preserved.

stern character representation a steadily progressing, 25 In the image used for character representation

The clock signals of the character generator provide a high level of accuracy for the

conditional horizontal beam deflection is required. horizontal deflection signal of the beam required,

In addition, this known method allows the ches by the superposition of the horizontal deflection

Character representation does not use a signal from the ^ sawtooth generator with the from

homely commercial television tube for the signal generated by the 30 X modulation sawtooth generator

display. len on an approximately step-shaped rising flank-

The invention is based on the object of having. This modulated horizontal deflection signal, a simple circuit arrangement by means of which low-frequency and high-frequency components contain an improved representation of characters on the, is to be amplified in order to obtain the required display screen of a cathode ray tube and a deflection energy for the electron beam, sere Legibility of the characters is achieved by increasing the accuracy requirements for the horizon due to the lower-frequency and higher-frequency characters and the components in the deflection signal due to the increased horizontal distance between two characters. This anti-beam deflection, which improves the typeface, is used to generate the modulation, provided that the complex and character generator, a time control circuit or circuitry that is expensive as a result, especially in another information input point in the same deflection amplifier, is required by the horizontal deflection signal.
clock signals issued in a timely sequence, which serve to form the grid columns, is that the circuit arrangement according to the invention can be designed so that the block division in the same 45 order is designed so that it moves with the smallest of fields in the character generator and in the runtime memory can be produced economically and yet it is maintained that the number of conditions conveyed in a line is fully and reliably fulfilled, the characters that can be represented are not reduced and that this economic improvement is thereby that the height of the characters remains the same. In addition, it is enough that the ^ deflection amplifier a feedback should the new circuit arrangement not require a large processing circuit for the low frequency, from the X-saw effort, and it should subsequently still tooth generator generated horizontal deflection signal in already delivered display devices that does not have to compensate for non-linearities have the improved character representation, for and that the amplitudes of the X-modulation-Sä-Purpose of modernization have to be incorporated. This object is influenced according to the invention by an envelope generator in order to eliminate the fact that a counting device operated by clock signals is provided to eliminate the non-conduction occurring during the signal superposition, the counting capacity of the column nearities.

number of a character grid field and the following is a brief description of the

each character a trigger signal for an additional circuit arrangement according to the invention to improve

Z-modulation sawtooth generator emits, the 60 best character representation.

train on the deflection signal of the first X-sawtooth from the periodically in the same cycle times and stegenerators for each character grid field successive y-synchronization signals at higher frequency ,. quent asymmetrical sawtooth pulses generated, which cause the vertical beam deflection, a gently sloping flank from the first to the will act as a reduction stage last character column of a character and a steep 65 counting device derived control signals leading to the rising Have flank for the gap, generation of trigger signals are used, which the Bedaß these higher frequency sawtooth signals determine the beginning of a character position. This rising edge of the deflection signal from the AT-sawtooth-pulse signals are used to trigger the ^ -modulation-,

Sawtooth generator, which sawtooth-shaped negative Pulses generated with the same length of time, corresponding to the length of time one of the Character generator of presented characters. These sawtooth-shaped output signals from the X-modulation sawtooth generator, the number of which corresponds to the number of characters in a line are used to modify (modulate) the relatively low-frequency, Horizontal basic deflection signal generated in the sawtooth generator for line-by-line deflection of the electron beam, whereby a resulting approximately step-shaped deflection signal results whose rising edge effective in the writing process is more or less steep having. This modulated horizontal deflection signal for the ^ deflection system of the picture tube has in the the areas of the leading edge assigned to the character columns have a lower slope and in the areas which are assigned to the spacing gaps, a greater steepness. This causes the beam with a horizontal movement across the screen in the area of the character columns slower and is disengaged faster in the area of the spacing gaps. Since the cycle times for the vertical beam deflections but are the same, it follows that the different horizontal jet velocities During a cycle time the beam covered different horizontal distances will. This causes the character columns to become narrower and the spacing columns wider than at a uniform horizontal deflection of the electron beam, as is known in the case of: - ZDiIdschinngeräte the case is. The horizontal deflection signal, which is roughly modulated in a stepped manner, thus becomes achieves that the jet speed slows down in the area of the character gaps and in the area of the spacing gaps is increased, so that the average speed of the horizontal beam movement across a grid, however, is the same. The circuit arrangement according to the invention results thus a compression of the character columns by reducing the spacing between and a spreading of the spacing gaps by increasing the distances between the last and the first column of characters that are adjacent to one another. The result is an aesthetic, flicker-free and pleasantly legible writing, this result being achieved without reducing the number of characters to be displayed Characters decreased or memory capacity increased.

In order to obtain a uniform character representation on the screen, it is as already before mentioned required that undesirable non-linearities or distortions in the deflection circuit be avoided. In order to obtain an economical implementation of such a deflection circuit, it is advantageous to have the modulated horizontal, approximately staircase-shaped deflection signal in a single Generate amplifier, the resulting horizontal deflection signal from the sawtooth-shaped relative low-frequency base deflection signal and its rising edge superimposed on higher-frequency signals is formed. For economic reasons it is desirable to have the smallest amplifier unit find the one that meets the requirements. As a result, some building units can be converted into Operates areas in which they no longer work linearly, and that one can correct these distortions additional circuitry is required. It was found that when creating the sawtooth-shaped Basic signal and when modulating this basic signal by the relatively high-frequency sawtooth-shaped Superposition signals also cause distortion, so there is a problem with the various Correct distortion of the horizontal deflection signal.

According to a further development of the invention, a simplified circuit arrangement is specified, which eliminates the various distortions of the horizontal deflection signal in a simple manner can be, both in the ramp-shaped basic deflection signal and in these to be superimposed higher-frequency signals, so that the desired staircase-shaped modulated undistorted horizontal Deflection signal results.

In a pattern made in accordance with the embodiment of this invention, these were found to be distorting on the sawtooth-shaped basic deflection signal effective non-linearity of the X-deflection amplifier eliminated by a feedback circuit, which is the linear rising edge of the supplied by the X sawtooth generator to the ^ deflection amplifier Basic deflection signal so distorted that the effect of the non-linearity of the X-deflection amplifier is compensated. In addition, when modulating the horizontal basic deflection signal due to the superposition of the higher-frequency sawtooth signals due to the non-linearity of the X-deflection amplifier resulting signal distortion dsd-rch prevents the amplitudes of the vom X-modulation sawtooth generator delivered superposition signals an envelope which is complementary to the non-linearity to be corrected is.

It is a further feature of the circuit arrangement according to the invention that the aforementioned Envelope is generated by an envelope generator, the triggering of which is synchronized with the resulting horizontal deflection signal and that its output signal in the X-modulation sawtooth generator in which it influences the amplitudes of the sawtooth signals to be superimposed, whereby the curve to be modulated onto the rising edge of the basic deflection signal arises.

The invention is described below using an exemplary embodiment with reference to circuit diagrams and drawings (F i g. 1 to 6) explained in more detail. It shows

F i g. i in block form a character display system that uses the circuit arrangement according to the invention is provided

F i g. 2 A and 2 B the grid-like arrangement of the characters to be displayed in the typeface, generated by the circuit arrangement of the known design (^ 4) and by a modified circuit arrangement according to the invention (B),

F i g. 3 shows some waveforms in the modified circuit arrangement;

of the signal trains represent:
A) vertical synchronization signals generated by the timing control circuit,

B) 6 bit signals, derived from the signals mentioned in (A) above,

C) sawtooth signals of the X modulation sawtooth generator, each triggered by a signal shown in (B),

409 524/328

D) the steadily rising edge of the horizontal basic deflection signal, which is supplied by the X-sawtooth generator, and underneath the rising edge of the resulting horizontal deflection signal, modified by the modulation, which acts on the Z-deflection system of the cathode ray tube;

F i g. 4 shows, in block form, a character display system with circuitry for elimination of non-linearities, according to a further embodiment this invention,

F i g. 5 is a detailed circuit diagram of part of the circuit arrangement according to FIG. 4, which for Achieving the linearity of the resulting horizontal deflection signal is used,

F i g. 6 shows some operating curves of signals of the in FIG. 5 shown circuit arrangement.

In Fig. 1 shows a character display system in block form, in which the circuit arrangement according to the invention is applied. This circuit arrangement according to the invention is shown in the block diagram of FIG. 1 highlighted by a wide line width of the circuit blocks and the connections for the purpose of a better overview. The characters to be displayed on the screen arrive in a coded signal sequence (BCD) in a character generator 12 and are converted by this into a sequence of video signals which represent the characters to be displayed. The electron beam is scanned brightly by means of these video signals. The character generator 12 provided in this character display system is already known to the person skilled in the art. The above-mentioned video signals appearing in a row are either used directly to control the brightness of the electron beam, or they are entered into a transit time memory 23 for the purpose of subsequent display of the characters on the screen of the tube 10. The character generator 12 is connected to the transit time memory 23 by a time control circuit 14 synchronized, while the transit time memory 23 receives clock signals over the line 25 from the time control circuit 14 with constant time.

The explanation of the F i g. 1 is first interrupted, and for a better understanding the following in FIG. 2 A illustrated typeface of the known circuit arrangement explained. This Figure 2A shows four characters, each character being formed by dots in a grid of five vertical columns of characters, in a manner which will be described in more detail later. In this line section (A) four characters HERE are shown, each character being formed from dots which are arranged on a grid which has vertical columns of characters. Adjacent characters are separated from one another by a spacing column, also known as a blank column. This typeface shows that the separation distance between two adjacent characters is obviously too small and that this makes it difficult to recognize the characters and that there is a possibility of incorrect reading.

The description of the circuit arrangement according to FIG. 1 continued. From the exit of the transit time memory 23, the video signals reach the video amplifier 27 via the line 24 and from there directly onto the cathode or the control grid of the cathode ray tube 10 for light scanning of the electron beam. From the time control circuit 14 get ^ -Synchronisiersignale over the line 33 to the ^ sawtooth generator 44 and Y synchronizing signals via line 37 to the Y sawtooth generator 39. The ^ -Synchronisiersignale appearing on the line 33 are used for rhythm control the deflection signals generated by the X sawtooth generator 44, which for the horizontal Serve beam deflection over a line. The Y synchronizing signals appearing on line 37 are required for the rhythm control of the Y-sawtooth generator 39, which in the same time Result signals for the vertical beam deflection generated. This circuit arrangement described above is already known and is not yet used in the character display system whose typeface is is satisfactory is used.

According to the invention, this known circuit arrangement for displaying characters is provided by a circuit branch supplemented, which consists of a counter 62, an AT modulation sawtooth generator 58 and a modulation signal amplifier 53 is formed. The following is the explanation of the block diagram the F i g. 1 continued and the interaction of the known circuit arrangement with the new circuit arrangement described.

The already mentioned Y-synchronization signals generated by the timing control circuit 14 also arrive to the Y sawtooth generator 39 also via a line 64 to a counting device 62, a so-called N-bit ring counter that sends a signal to its after every six Y synchronization signals received Output. This output signal is the trigger signal for circuits in the invention Circuit arrangement for modifying the horizontal deflection signal, which will be explained in more detail later is described. Each cause six of the aforementioned Y synchronization signals six vertical beam deflections that make up a character grid, the first through the fifth Deflection form the character columns and the sixth deflection form the spacing column or empty column.

The F i g. 2 B shows a more legible typeface the characters displayed on the screen, which with the circuit arrangement according to the invention was achieved. This character representation assumes that the one used to write a Line required electron beam while moving at a relatively slow speed from its rest position moved horizontally from left to right across the screen, each time to be displayed Characters corresponding to the five vertical columns of characters in a character grid, five vertical ones Performs distractions. In FIG. 2B are the vertical character columns 47 as vertical lines shown. In the practical example, however, the character columns 47 are slightly inclined because during the vertical beam deflection the beam also moves to the right in the horizontal direction. In addition, the line pattern is not visible because the beam is only light-scanned by the video signals will. In this improved mode of operation, the electron beam generates one for each character 43, 45 Group of five vertical grid lines of the character columns 47, being light-scanned by the video signals will. The five character columns 47 are followed by a sixth vertical column after the same cycle time Beam deflection that is completely darkened

J 549 759

11 12

which the spacing columns 26 in the character space are clock signals to the five character columns 47

sterfeld forms. The spacing column 26 is assigned in the grid field and the fields in the line

a horizontal separation of neighboring blocks in which the video signals for the

th characters reached. characters to be sent are stored. For example

From a character to be displayed, which is formed on the 5 for the vertical synchronization pulses, a number of raster-shaped pulse repetition frequencies of 15 360 Hz selected ordered light-scanned points can be created on the screen. It has already been mentioned that the control signals associated with this symbol, synchronizing pulses, are also stored in the symbol generator 12 for the counter. According to device 62, this iV bit ring counter acts as the typefaces of FIG. 2 are simple scaling stages in the character generation and after each gate 12 first outputs the signals for the character H (43), six received clock pulses (Y-synchronizing included. This is followed by the character E (45) and signals) at its output on the curve B continues until all of the information to be displayed is output. Curve B of Fig. 3 is indicated. A comparison of the two typefaces shows that such an output signal in each of FIGS. 2A and 2B shows how the width of the characters is reduced by the present time interval between the sixth vertical deflection signal and the first vertical deflection signal and the spacing the next character, enlarged to the neighboring character, appears. This initial point was made and that it also results in an aesthetic signal to initiate the Af modulation saw scissors typeface. This advantageous effect of the tooth generator 58, which is a common one, is achieved by the fact that, in addition to the counting device 20, there is a counter /? C generator and another sawtooth generator 58 shown in FIG high-frequency sawtooth feed circuit arrangement according to FIG. 1 created with a single signal. This signal curve C shows in Begen. The counter 62 (an N-bit ring counter from the first to the second vertical synchronizer), which actuates the Y synchronizing signals to increase the signal quite steeply and in the Bewird, pushes through its output signal the X modulus of the following five Vertical synchronization sawtooth generator 58, which then signals a flatter sloping edge profile. In the case of a relatively high-frequency negative sawing signal shown in curve C, the tooth-shaped signal can be generated, which then carries the low-frequency horizontal deflection signal with the relative amplitude of the sawtooth voltage minus 15 volts and which can be set using a potentiometer , ches generated by the X-sawtooth generator 44 3 ° The rising edge of the output signal from the X-Säwurde, is combined. This combined signal gear generator 44, which serves as the basic deflection for the horizontal beam deflection in the regions over a line length, is to be continuously marked, for which character positions are provided, the curve 55 in FIG. 3, which shows a flatter course, as a result of which the stepped curve 188 lying in this area shows the anche a slowed horizontal beam deflection 35 leading edge of the resultant due to the superimposition is brought about. In the areas of the character grid fields there is a horizontal deflection signal, which, however, is not the one which is shown to scale with the horizontal character separation distances.

which correspond, has the combined or result- The in the F i g. 1 shown circuit arrangement horizontal deflection signal contains a considerably larger size than is already known from a Y-deflection shell Incline, which creates a 40 device in these areas, which the Y-sawtooth generator 39 and the Including increased horizontal beam deflection speed downstream Y-deflection amplifier 59, there and thereby a broadening of the separating Y-synchronizing signals generated in the timing control station between adjacent characters. circuit 14, arrive as clock signals in time

In FIG. 3 are in the same sequence over the line 37 to the Y-saw

to each other some essential signal curves of the 45 tooth generator 39, whose output signals the

Circuit arrangement for the horizontal beam table - downstream Y-deflection amplifier 59 amplified,

recorded. From the curves show: The Y deflection amplifier 59 supplies a series of sa-

A) Vertical synchronization signals, also as Y-syn- tooth-shaped signals for the vertical deflection system

called chronisiersignale, which also to the stem 22 of the picture tube 10.

Counting device 62 arrive, 5 ° The time control circuit 14 supplies over the line

B) Output signals of the counting device 62, 33 ^ -Synchronisiersignale to the X-sawtooth genera-

C) from the Z modulation sawtooth generator 58 gate 44, whose output signals the X deflection amplifier

generated output signals, ker 51 amplified. This reinforced sawtooth-shaped

D) the linearly rising edge of the X-saw output signal serves as the basic AT deflection signal for the tooth generator 44, which is relatively low-frequency 55 writing of a line, and its rising edge-frequent deflection signal 55, the lower one being the higher-frequency sawtooth-shaped Si Curve 188 shows the rising edge of the combined signal (curve C, FIG. 3) superimposed, which in the ned horizontal deflection signal, which is Z-modulation sawtooth generator 58 and that from the superposition of the curve (C) with downstream Af- Modulation signal amplifier 53 of curve 55 forms. 60 were generated. The superposition of the signals C,

In the following, the aforementioned Si-D55 takes place at point 63 of FIG. 1, so that von gnalkurven are described in more detail. At the curve from this point 63 onwards as curve 188 in line A of FIG. 3, every sixth Y or vertical FIG the image is slightly higher than the five intermediate signals 65 screen tube 10.

shown. These somewhat higher signals are determined by the X-modulation sawtooth generator 58

the gap 26 or the distance between holds its trigger signal from the counter 62,

two adjacent characters 43, 45, and the five small characters which are connected via lines 37 and 64 from the

13 14

control circuit 14 Y-synchronizing signals into glei- zontal basic deflection signal is converted into Receives cycle times. This results in the example in the ^ "sawtooth generator 44 created, F i g. 2 B shown raster-shaped beam guidance, since it is anelche by precisely timed ^ "- synchronizing signals five vertical beam deflections in one, which via line 33 from the Character grid field, while the beam is thereby provided 5 timing circuit 14. That from is steered horizontally relatively slowly, with X-sawtooth generator 44 generated sawtooth-shaped a compression results because their distances now signal reaches the X-Ablenkenger via line 48 are. This is followed by a sixth vertical amplifier 50 and from its output in modifying beam deflection, which takes place in the time in which the ter form via the lines 61 and 54 to the X-Abhorizontale Beam deflection with increased speed steering system 20 of the screen tube 10. The advance happens. In this embodiment, the expression mentioned that the line 48 was, as already described, after every six sawtooth-shaped horizontal deflection signals in modifi-vertical synchronizing signals the X-modulated form appears on line 52, stating tion sawtooth generator 58 activated. It goes without saying that in the deflection amplifier 50 that of the X-sawtooth it is also possible, depending on the number of generators, 44 generated sawtooth-shaped basic arresters to be shown on the screen of the tube 10- steering signal is modulated so that at the output of the to choose a different signal ratio for the characters. X-deflection amplifier 50 a resulting horizontal

The following appears in connection with the deflection signal, its rising edge

F i g. 4.5 an advantageous further development which is in the form of an inventive step. The X deflection amplifier 50 is equipped with the circuit arrangement according to FIG. 1 20 is provided with a .Y modulation input that is fed through

described in more detail. line 56 with the output of the AT module

The F i g. 4 also shows that a sawtooth generator 58 is connected in a block circuit. This The principle of an improved character representation X-modulation sawtooth generator 58 is illustrated by device according to the invention, as already initiated before synchronization signals on the line was described standing. For character display 25 60 are, and it gives at its output for each Zeiomen A sawtooth-shaped modulation is applied to the cathode ray tube 10 synchronously and from the timing control circuit 14 dependent signal. The sync signals on line 60 Signals which, as already mentioned, trigger the X-modulation sawtooth generator came from the character generator 12. The time generator 58 can fetch directly from the timing control circuit 14 12 is a transducer and forms the ones that are routed to 30, but for a better understanding they are Line 16 in the incoming 5CD code circuit arrangement is used to synchronize the information in video signals, which are supplied as signals by the counter 62 (which Light-dark tactile signals via line 18 to again an iV bit ring counter), which is through the on the Screen tube 10 get and in the merging line 64 incoming Y-synchronization signals ken is switched on cyclically with the beam deflection by the deflection system. It was already first Af 20 and Y 22, depending on the time, thinks that in this embodiment a time control circuit 14 the character display on the grid field five vertical character columns or Effect the screen of the tube 10. The illustration contains five vertical deflections and one of the characters and the achievement of a between the spacing column and that of the horizontal separator mark the distance was already protruding between two characters by the obscuring on the basis of FIG. 2 describes from which constant spacing gap is formed. The vertical view is that in this embodiment deflections of the beam to generate the characters Character grid field five vertical character columns are made in each case in the flat gradient contains and a spacing column which defines the horizontal areas of the horizontal deflection signal, and tal separating distance between two characters. 45 becomes the grid column for the character separation distance

It was also described above that in the time in which the modulated horizontal deflection signal by the circuit arrangement according to the invention has a steeper edge, which generates a modulated horizontal deflection signal, an increased deflection speed of the electron beam, which means an approximately step-shaped course in itself. This vertical deflection of the electron has a rising edge. The steps of the resulting beam for generating the horizontal deflection signal produce the line separation distance in the is accordingly the sixth vertical raster column in the line areas with a low gradient, a compaction of the raster field. In this embodiment, the vertical column of characters and thus a Redu- "N" = 6, which means that after every six verticalization of the character width and in the areas where the beam deflections show a reset of the counting switch, the dark-colored device is located 62 takes place and that following a new scanned spacing column 26, which begins a spreading cycle. Resetting the counters results in character spacing, see Fig. 2 B. device 62 is carried out by an appearing on line 66

The circuit arrangement according to FIG. 4 contains the signal "delete" which the counter 62

also a Y-deflection system 40, which corresponds to the in the time control circuit 14 with the character

F i g. 1 already mentioned corresponds to. Synchronized by the time 60 generator 12 to ensure that

control circuit 14 in turn reach the same characters 43, 45 to be displayed the corresponding

Y-synchronization signals are assigned to time intervals via the lines of character columns 47 in the grid field

device 37 to the sawtooth generator in the Y-deflection system.

system 40, from which via the line 41 in succession.

Another, in a predetermined sequence, sawtooth-shaped external circuit arrangement is the .Y-Modulation-Sä-

Steering signals to the vertical deflection system Y 22 of the tooth generator 58 with circuit devices

Screen tube 10 are supplied. see what the effects of non-linearity

Compensate the hori- times of the Af deflection amplifier 50 required to write a line. to

15 16

this compensation device also includes a

Envelope generator 68, which synchronizes with the ren, in which the fed back signal to the input

Z-deflection amplifier 50 cooperates and is fed by sawtooth-shaped signal through algebraic

whose horizontal output signals are added via the line addition in order to

Gen 61 and 70 is triggered and the need to achieve the result of the rising edge 112 is eliminated

output signal via line 72 to an input by compensating only the influence of nothing

of the X modulation sawtooth generator 58 supplies. linearity of the tube 80 on the basic deflection

The mode of action of this in FIG. 4 by a signal for the horizontal beam deflection, but The dashed frame does not indicate the influences of the non-linearity of the Z-deflected element Circuitry 74 is shown in FIG. 5 io amplifier 50, especially that of the dissimilar Verunter Reference to the FIG. 6 recorded reinforcement of the tube 80, which by the modulation Neten operating curves in more detail or through the superimposition of the relatively Niederfreläutert. quent basic deflection signal with the higher frequency

This in FIG. 6 sawtooth-shaped signals denoted by A , B, C, D and F result. These

Neten operating curves represent voltages, which 15 higher-frequency sawtooth-shaped signals, which

is generated at the points labeled A , B, C, D and E in the Z modulation sawtooth generator 58

the circuit arrangement F i g. 5 are present. It will come via a line 56 and a

it should be noted that these curves are only used for the second input of the Z-deflection amplifier 50

Illustration and for a better understanding of the grid 94 of the tube 80, where it receives the anode current

serve different circuits and that they do not »o this. Modulate tube 80. Also with this module

are shown to scale. lation arise from the non-linear amplification

The one shown in FIG. 5 simple Z-deflection of the tube 80 shown unwanted distortions of the module amplifier 50 contains a tube 80, which a compensated output signal, which is an imprecise dartode. To reduce the anode current in the position of the characters and those of the tube 80 and to protect their anode 82 in the 95 must be eliminated. If these distortions arising in the anode circuit of a matching transformer 84, des modulation were to be swept on the secondary side with the output lines 54, the above-mentioned feedback or 54 'is provided. These output lines -54, pelungsrietzwerk also for higher frequencies emp-54 'are identical to the line 54 in FIG. makes more sensitive, then there is the disadvantage that the F i g. 5 further shows that the output lines 30 lead the output signals of the Af deflection amplifier at Lh-54 or 54 'to the X deflection coils 20 of the picture rem end 50, inadmissible overshoot peaks 120, screen tube 10, and also have an ab-122 As can be seen from curve B, FIG. 6, to branch line 70 the output signals as feeders. Z-deflection signals of this kind are not usable and synchronization signals on the envelope curve generators are usable, and the capacitance values tor 68 have therefore been reached. 35 of the capacitors 108, 110 in the feedback

To compensate for the non-linearity of the Z deflection network, which also acts as a filter circuit, amplifier 50 is so low that the linear rising edge is kept so that no such pronounced excess of the horizontal oscillation peaks 120, 122 supplied by the Z sawtooth generator 44 occur,
The basic deflection signal would be adversely distorted. To linearize the modulation, the X deflection amplifier 50 has a compensation 40 based on a feedback method in the above circuit, the arrangement and type of which is explained below using a network. That waived at the An. According to the development of the invention, the anode signal applied to the transformer 84 is applied to eliminate the adverse effects of the is fed back via a feedback network to the non-linearity of the X modulation sawtooth generator point A of the input terminal 48, 45 gate 58 is operated in such a way that it is on in which the deflection amplifier 50 uses a compensation method for the influence of the sawtooth-shaped basic deflection signal generated. This feedback network eliminates corrugation. The F i g. 5 shows that the X-Moches also forms a filter circuit, like the dulation sawtooth generator 58 a PNP-Transi-Fig. _: 5 shows, consists of the resistors 102, 104, 50 contains disturbance 130, which is in a grounded emitter-106 and the capacitors 108 and 110. The circuit is operated and that to the base of point A through the feedback network korn-transistor 130 leads the line 60, via which yaw occurring voltage curve is passed in the course-kick-impulse 132 (see curve C of the venzug / 4 of Fig. 6 recorded. This sawtooth Fig. 6). These trigger pulses 132 are in the shaped voltage signal contains a rising edge 55 counter 62, as already described, 112, which is no longer linear, but one generated. These push pulses 132 cause when it has a slight upward curvature. These non transistor 130 that has its collector (point D of the linearity of the rising edges 112 g to allow it to react F i. 5) is connected to ground potential (see Fig. Purpose effect of the feedback signal from the Rückkoppe- F i g. 6, curve D , Signal sections 134). Through this circuit network, and through this circuit measure, the edge distortion with the collector is the influence of the non-linear capacitor 136 connected to the transistor 130 divides the X-deflection amplifier, especially that of the references discharged. A complete capacitor relief in the tube 80, compensates. This charging does not take place, however, because the condensate wanted distortion of the rising edge 112 is in the gate 136 on the other side of the negative Git tube 80 due to the unequal gain 65 of the tube 80; this grid is pre-compensated so that at the output of the tube 80 a voltage is applied to the point 138 via a resistor in a sawtooth-shaped basic deflection signal.
that has a linear rising edge. As soon as the pulse-shaped trigger signal 132 fails

If more is applied to the base of transistor 130, this transistor 130 blocks, and the capacitor 136 is charged by an envelope generator 68 at time 142 (see FIG. 6, curves C and D). This circuit arrangement after each trigger signal 132 generates ramp-shaped modulation signals 144, 146, 148 determined in the envelope generator 68.

The capacitor 156 is charged cyclically, once in each case in a complete deflection cycle in the horizontal or X-direction of the electron beam for writing a line. For this purpose of charging the capacitor, the Z-deflection amplifier 50, which serves as a convenient energy source, is connected to the envelope generator 68 via the line 70. It can be seen from curve B in FIG. 6 that a negative-going cut-off voltage 160, 162 is generated at the end of the modulated sawtooth-shaped deflection signal. It is a feature of this inventive circuit arrangement that this cut-off voltage 160, 162 etc. is used to charge the capacitor 156 in each horizontal deflection cycle. The capacitor 156 is charged via the line 70, the resistor 164, the coupling capacitor 166 and the diode 168. After the cut-off voltage 160, 162 has decayed, the coupling capacitor 166 discharges via the diode 169 to ground, and the capacitor 156 discharges slowly through the resistors 152, 154 and through the circuit of the Z-modulation sawtooth generator 58. The resulting charge and discharge cycle of the capacitor 156 is determined by the aforementioned i? C elements and is shown as a curve of the capacitor voltage with the edges 170, 172 and again 174, 176 in FIG. 6, curve E recorded.

A part of the voltages of the curve train E, which has the shape of an envelope curve, is tapped at the potentiometer 152 and via the resistor 150 to the collector point D in FIG. 6 led. This has the effect that the operation of the Z-modulation sawtooth generator 58 is influenced by this envelope voltage supplied at the collector point D , because this envelope voltage is superimposed on the periodic sawtooth charge and discharge voltage of the capacitor 136 generated by the transistor 130. The signal on the grid line 56 corrected in this way corresponds to the IC curve , the envelope curves 178 and 180 shown in FIG. 6, curve D. These envelope curves 178 and 180 receive the voltage curve of the capacitor 156 impressed, corresponding to point E in the envelope curve generator 68. The envelope curves 178, 180 of curve D are similar in their course to the flanks 112 of the horizontal basic deflection signal of FIG

ίο Curve A and adjustable to compensate for the non-linearity in the gain of the tube 80. It should be noted here that the course of the edges 112 and the envelopes 178, 180 is a mirror image of the course of the gain of the tube 80. However

»5 the course of the envelopes 178, 180 is not exact equal to the course of the amplification factor for the tube 80, because by the action of the different Components may have a slight deviation. A selection of these components

ao ments and by adjusting the potentiometer 152, however, it is possible, at the starting point Β of the -Y deflection amplifier 50, a step-shaped horizontal To receive the deflection signal as an output signal in which the undesired non-linearities or Distortions are eliminated and which is sufficient for practical purposes.

In FIG. 6 shows curve B the corrected sawtooth-shaped horizontal deflection signals 188 and 189, which have a very good linear leading edge and are modulated in a step-like manner. This favorable curve shape results firstly from the compensation of the non-linearity of the AT deflection amplifier 50 through the distortion of the basic deflection signal of curve / 4 and secondly through the change in the amplitudes of the sawtooth-shaped signals to be superimposed during the modulation according to curve D. The result of this improved The circuit arrangement with the two compensation devices combined with one another for walling up the distortions in the Z deflection amplifier 50 is a uniform arrangement of the character columns 43, 45 in a character grid, which corresponds to the flat step areas 190, 196 in curve B, FIG. 6, while the spacing columns 26 for the character separation distance from the steeper flanks, e.g. B. 192, 198, in curve B can be created. It should be noted that the in FIG. 2 characters and character spacing shown are not to scale in their size, but that they only serve as an aid to explaining the circuit arrangement.

1 sheet of drawings

Claims (4)

Patent claims: 1. Circuit arrangement for the line-by-line display of characters on the screen of a cathode ray tube in a grid field which contains several character columns for each character and at least one spacing column that forms the separation distance between two characters, by means of light-scanned video signals during the vertical, which occur in the same time sequence and form the columns Beam deflections with a simultaneous horizontal beam deflection, consisting of an A 'sawtooth generator that generates the deflection signal leading the beam in the horizontal direction over the length of the line, a Y-sawtooth generator that generates the signals that deflect the beam in the vertical direction over the height of the characters, a character generator , which supplies clock signals to the Y-sawtooth generator and video signals for the picture tube at equal time intervals and a timing control circuit for synchronizing the deflection and video signals, characterized in that one of clock signals (A, Fig. 3) actuated counting device (62) is provided whose counting capacity corresponds to the number of columns of a character grid field and which emits a trigger signal (B) for each character (43, 45) to an A "modulation sawtooth generator (58), which is referred to on the deflection signal (55) of the X sawtooth generator (44) generates higher-frequency, asymmetrical sawtooth pulses (C) for each character grid, which have a gently falling edge from the first to the last character column (47) of a character (43, 45) and a steep one rising edge for the gap (26) have that these higher frequency sawtooth signals (C, 144, 146, 148) are superimposed on the leading edge of the deflection signal (55, 112) from the A'-sawtooth generator (44) and that the amplitudes of the sawtooth pulses to be superimposed (C, 144, 146, 148) are chosen so that after the superposition, the resulting horizontal beam deflection speed is slower in the character columns (47) and faster in the spacing columns (26), so there ß compressed spaces between the character columns (47) and spread spaces at the spacing columns (26) form. 2. Circuit arrangement according to claim 1, characterized in that the, Y-sawtooth generator (44) generated sawtooth-shaped horizontal basic deflection signal (55) at an input an A 'deflection amplifier (50) having a circuit which influences the non-linearity of the A 'deflection amplifier (50) to the basic deflection signal (55) eliminated that an a second input of the A 'deflection amplifier (50) from the A "modulation sawtooth generator (58) the sawtooth-shaped higher-frequency superimposition signals (C, 144, 146, 148) are supplied, whose amplitudes are used to compensate for the non-linearity influences of the λ "deflection amplifier (50) change in the form of an envelope curve (178, 180), and that the ^ deflection amplifier (50) at his Output (54) the stepped modulated deflection signal (188, 189) to a matching transformer (84) for the ^ deflection system (20) of the cathode ray tube (10) supplies. 3. Circuit arrangement according to claim 2, characterized in that the circuit for Compensation of the non-linearity influences on the basic deflection signal (55) a feedback network is that distorts the leading edge (112) of this signal. 4. Circuit arrangement according to claim 3, characterized in that for generating the Envelope (178) for the amplitudes (144, 146, 148) of the sawtooth-shaped superimposition signals (C) the A "modulation sawtooth generator (58) influenced by an envelope generator (68) and that this envelope generator has an ÄC circuit branch which is derived from the output signal of the A 'deflection amplifier (50) is fed.